Bluefin-21 has made six deep-sea scanning runs but has detected nothing.

Critical juncture ... Malaysia's acting Transport Minister Hishammuddin Hussein said the MH370 salvage mission would be reassessed if nothing is found in the next 48 hours.Source: AP

The next 48 hours in the search will be critical, Malaysia’s acting transport minister said.

“Whatever happens in that period, we will then regroup and discuss our next move,” Hishammuddin Hussein told reporters in Kuala Lumpur on Saturday.

After more than six weeks without any sign of wreckage from the missing plane, the current underwater search has been narrowed to a circular area with a radius of 10km around the location in which one of four pings believed to have come from the black box recorders was detected on April 8.

Time is running out ... Phoenix Autonomous Underwater Vehicle (AUV) Bluefin-21 is craned over the side of Australian Defence Vessel Ocean Shield in the search for the missing plane.Source: Supplied

The Australian government was also reported to be in talks with Malaysia to decide who will handle any wreckage that may be recovered, including the critical black box recorder.

Malaysia was drafting an agreement “to safeguard both nations from any legal pitfalls that may surface during that (recovery) phase,” the New Straits Times reported.

The government hopes the deal can be finalised soon and endorsed in a cabinet meeting next week.

The Australian government is studying the memorandum of understanding, it said.

“The MOU spells out exactly who does what and the areas of responsibility,” Malaysia’s civil aviation chief Azharuddin Abdul Rahman was quoted as saying.

Mr Azharuddin added that Malaysia would lead most of the investigation, with Australia and others helping.